The aims of the final year of this grant are to analyze the molecular basis for a variety of macrophage functions by means of selecting and studying somatic cell mutants or variants of continuous macrophage-like cell lines. Experiments will be carried out to investigate the nature of macrophage immunoglobulin and complement receptors, phagocytosis, migration and inhibition of secretion of neutral proteases, extracellular killing of tumor cells and intracellular killing of ingested parasites, as well as mechanisms of macrophage mediated tissue damage associated with cell-mediated immune reactions. A major goal is to understand the regulation of these phenomena, and particularly the role of products of activated lymphocytes such as MIF, pharmacological and hormonal agents.